1. Field of the Invention
The present invention relates to a converging element for an LED, and more particularly to a converging element for a light-emitting chip, which reduce a light-emitting angle of the light-emitting chip and enable the light-emitting chip to uniformly illuminate a light-receiving surface, so as to increase the energy of the illuminated area.
2. Related Art
In the manufacturing process of electronic elements, extremely fine metallic circuits or semiconductor structures need to be manufactured. In order to achieve this condition for the manufacturing process, the process and methods of lithography techniques are usually utilized. In a conventional lithography technique, a surface of a wafer is cleaned first, and then coated with a photo resist containing photosensitive chemical substance. Afterwards, a photo mask with a designed pattern is fabricated and placed on the surface of the wafer. Then, light rays emitted from a light source pass through a transparent area of the photo mask. The light rays passing through the photo mask react with the photo resist. This step is generally referred to as exposure.
As for conventional exposure machines, mercury-xenon short-arc lamps are mostly used as light sources. An ultraviolet light is emitted from a mercury-xenon short-arc lamp and passes through a transparent area of the photo mask. Then, a chemical change occurs between the ultraviolet light passing through the photo mask and the photo resist that reacts with the ultraviolet light. However, since a high voltage is required to actuate the mercury-xenon short-arc lamp and the required illumination power cannot be reached until a warm-up time elapsed, and thus, there are many limitations in usage.
In order to avoid the limitations of the conventional mercury-xenon short-arc lamp in usage, some manufacturers adopt an LED to replace the conventional mercury-xenon short-arc lamp. An LED can emit light immediately upon being powered on and does not require a high voltage as the mercury-xenon short-arc lamp. Meanwhile, a frequency band of the emitted ultraviolet light can be controlled by selecting a light-emitting chip. However, since the light-emitting chip is an extended light source, the extended light source emitted from the light-emitting chip needs to be converged into a parallel light source by a light transmissive lens, so as to avoid non-uniform illumination and change in the shape of light rays from the extended light source after passing through the photo mask when the LED is used as a light source for exposure. Meanwhile, in order to provide an ultraviolet light with a higher power to replace the conventional mercury-xenon short-arc lamp, a large-sized high-power light-emitting chip needs to be used. Therefore, a converging element needs to be designed for the large-sized high-power light-emitting chip, such that the light ray emitted from the light-emitting chip through the converging element becomes a parallel light.